158 FUNGI. 



sometimes two or three, develop into sporangia-bearing threads, 

 while the rest are short, pointed, and form a tuft of rootlets. 

 Sometimes these rootlets reduce themselves to one or more 

 rounded protuberances towards the base of the sporangia-bear- 

 ing threads. 



There are often also a certain number of the branches 

 which had acquired a clavate shape, and do not erect 

 themselves above the surface, instead of producing a fertile 

 thread, which would seem to have been their first intention, 

 become abruptly attenuated, and are merely prolonged into a 

 mycelial filament. Although in other species chlamydospores 

 are formed in such places on the mycelium, nothing of the kind 

 has been traced in this species, more than here indicated. Occa- 

 sionally, when germination is arrested prematurely, certain 

 portions of the hyphae, in which the protoplasm maintains its 

 vitality, become partitioned off. This may be interpreted as a 

 tendency towards the formation of chlamydospores, but there is 

 no condensation of protoplasm, or investiture with a special 

 membrane. Later on this isolated protoplasm is gradually 

 altered, separating into somewhat regular ovoid or fusiform 



FIG. 93. Zygospores of Mucor phycomyces. (Van Tieghem.) 



granules, which have, to a certain extent, the appearance of spores 

 in an ascus, but they seem to be incapable of germination. 



